The waste hierarchy is a concept from the circular economy field, which says that landfill of waste should be the ultimate option, after having tried reusing, repairing, and recycling.

He said CCU was a "really interesting solution", in particular when comparing it to CCS, which requires paying someone to store the CO2.

"If we can turn CO2 into something we could sell, we would be incentivised to do it," said Knight.

From cola to tomatoes

CCU is already applied in some sectors.

The CO2 in fizzy drinks is sometimes captured from industrial processes.

In the Netherlands, CO2 from industries operating in the port of Rotterdam is transported to the nearby Westland area, where it is used as a literal greenhouse gas, to help stimulate the growth of vegetables.

The EU is getting ready to increase its support for the development of CCU through a new Innovation Fund that will be part of the Emissions Trading System (ETS) from 2021 onwards.

Originally, the European Commission proposed that the innovation fund would be open only to CCS initiatives and "demonstration projects of innovative renewable energy technologies.

But both the European Parliament and the Council of the EU, where member states meet, propose that CCU projects should also be eligible.

The EU institutions will meet again next Wednesday (8 November) to negotiate further on the ETS.

A spokeswoman for Estonia, which holds the six-month rotating presidency, said "agreement is yet to be reached" but a source in the parliament said the inclusion of CCU in the fund was "not controversial" and that the institutions agree.

"We are pretty sure, let's say 99.5 [percent], ... that CCS and CCU will be part of that Innovation Fund," EU commission official Mark van Stiphout said last Thursday (26 November) at a conference on CCS in Rotterdam.

It is not entirely clear why CCU was not originally part of the commission proposal, but its proposed inclusion has been welcomed by industrial lobby groups.

The latest compromise text on the innovation fund specified that CCU projects eligible should be "environmentally safe" and contribute "substantially to mitigate climate change".

What substantially means will have to be further defined.

Greenwashing

Jonas Helseth, of the environmental lobby group Bellona, recently told EUobserver that some kind of "classification" is needed.

"CCU is a way too wide concept. If you try to approach that with one size fits all measures from governments, then we are going to get a lot of greenwashing and bad stuff, that's for sure," he said.

At the Rotterdam conference, Jacek Podkanski, a senior engineer at the European Investment Bank (EIB), said the bank would finance CCU projects "in theory", but that each project would have to be assessed on a case-by-case basis.

A lot depends on the life cycle of the product made with CO2, and the period during which the CO2 is kept out of the atmosphere.

If the CO2 is put in a product but then released to the atmosphere a few years later, the procedure has done little to help limit climate change.

CO2-to-fuels

One CCU application in that category that worried Helseth is using captured CO2 to make fuels.

The EU has funded research into this, through its Horizon 2020 science fund.

Steelanol, a project that tries to produce bioethanol from CO2 emitted by steel plants, received €10.2 million in 2015.

The biggest company involved in the project is ArcelorMittal. When this website asked to visit the project's site in Ghent and to receive more information, it was told to ask again at the beginning of next year.

CO2-to-fuels may also receive a boost through another piece of EU rules currently in the legislative pipeline: the renewable energy directive is currently being considered by the parliament and council.

Don't get too excited

Stuart McKay, head of CCS and hydrogen policy at the Scottish government said at the CCS conference in Rotterdam he was "a bit concerned" about CCU.

"What I'm worried about is that people outside this room may start to get confused and think that there is a choice between CCS or CCU. I recognise CCS as a climate mitigation tool. I don't quite recognise CCU in the same way."

Participants of the conference also seemed to agree that while CCU could be an addition to CCS, it was not likely to be a solution that can be applied to reduce emissions in the order of magnitude needed to avert catastrophic climate disruptions.

"I would not get too excited about that," said the EIB's Jacek Podkanski.

David Hone, chief climate change adviser at fossil fuel giant Shell, said CCU could help reduce the price of the technology to capture CO2, which could be a stepping stone to CCS.

He too warned against seeing CCU as a silver bullet.

"Large-scale utilisation can only be a dream of people who haven't done thermodynamics," he said.

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Investigation

The EU has spent at least €587 million so far on carbon capture and storage, and was willing to spend millions more. However, after a decade not a single power plant in the EU is currently using the technology.

Following an investigation into the Dieselgate scandal, the European Parliament recommended a single commissioner should be responsible for both air quality and setting industrial standards. But only the Greens want to commit to carry out that advice.